The problem could be the fuel is not good. Check that the fuel is fresh and can be used. If the fuel stays for more than four months it will not work. Make sure the fuel you have is the right fuel and that it is fresh.
I have the same jetski and I'm having the same probem. I put fresh gas, new spark plugs and a new battery and it's not even trying to turn over. It seems as if there is no gas is getting to the engine. Have you solved your problem???